An N-phenylarylsulfonylamide compound of formula (I) (R1 is COOH etc.; R2 is hydrogen, methyl, etc.; R3 and R4 are a combination of methyl and methyl, etc.; R5 is isopropyl etc.; Ar is thiazolyl, pyridyl, 5-methyl-2-furyl each optionally substituted with methyl; n is zero or 1), a synthetic intermediate for the compound and a process for its preparation. The compound of formula (I) binds to a prostaglandin E2 receptor, especially an EP1 subtype receptor, and antagonizes it. It is less affected by protein binding, so it has a satisfactory in vivo activity. Therefore, it is considered to be useful as an analgesic, an antipyretic agent, an agent for the treatment of pollakiuria (frequent urination) and/or lower urinary tract disease syndrome or an antineoplastic agent.